Patent GB-400717-A (GB)
Title: Pneumatic engines for operating doors
IPC: E05F15/56
Filed: 1932-06-17
Abstract: 400,717. Pneumatic door-operating mechanism. NATIONAL PNEUMATIC CO., 420, Lexington Avenue, New York, U.S.A. June 17, 1932, No. 17195. Convention date, July 24, 1931. [Class 65 (i).] A pneumatic engine for operating sliding doors, particularly of railway vehicles, is connected to the door by a lever which rotates in the plane of the door and lies'at right-angles to the edge of the door when the latter is closed ; the shaft carrying the door-operating lever also has a hand lever for ,manual operation, and a locking lever is provided to hold the door closed. Resilient means are preferably incorporated in the door-operating gear to allow the door to be stopped if its movement is obstructed, while the engine completes its stroke. The engine is of the differential type, pressure fluid being constantly supplied to a small cylinder and supplied to a larger cylinder through an electromagnetic valve, which may also be mechanically operated by the handlever. The locking means is released by a pneumatic-cylinder under electromagnetic control or by the hand-lever. The engine comprises a small cylinder 3 and a larger cylinder 4, the pistons 123, 124, Fig. 16, being connected by a piston rod 125 which has rack teeth engaging a toothed sector on the dooroperating shaft 38. The small cylinder is constantly supplied with pressure fluid, while the larger cylinder 4 is supplied and exhausted through a passage 81, which a piston 130, carried by a spring-pressed plunger 127 sliding in the piston-rod 125, closes towards the end of the door-opening stroke to cushion the movement of the door, the exhaust then taking place through a small passage 81a. Pressure fluid is supplied to the engine through a main valve 13, Fig. 2, from which pipes lead to the small cylinder 3 and to electromagnetic valves 11, 18. The valve 18, shown in detail in Fig. 12, controls the admission and exhaust of fluid for cylinder 4 ; it comprises a solenoid 93, with a movable core 94, and a valve rod 97, which has two valve surfaces co-operating with seats on plugs 99, 104 and is normally kept raised by a spring 103 to connect the pressure fluid pipe 84 to the cylinder through passage 81. When the solenoid is energized, its core 94 is attracted downwards and presses the valve rod 97 down to close the pressure fluid admission passage and open the cylinder to exhaust through passages 106. The lead 77 to valve 18 is taken through a switch 76, by which the valve can, when required, be cut out of a circuit controlling a number of engines. Valve 11 is similar to valve 18, except that its valve surfaces are reversed, so that the cylinder 19, which it controls, is normally open to exhaust and is supplied with pressure fluid when the solenoid of the valve is energized. The door D carries on its rear edge a vertical channel 34 and an arm 35. The channel 34 is engaged by a roller 43 on the end of a lever 42 which is slidably mounted in guides 41, Fig. 4, on the end of the shaft 38 of the engine ; the lever 42 is normally held extended by a spring 47, but this yields when the closing of the door is obstructed, so that the engine can continue its movement to bring the lever 42 horizontal, the door being closed by the spring 47 when the obstruction is removed. A locking lever 25, pivoted on the base of the engine, lies in the path of the arm 35 on the door when the latter is closed, so that the door cannot be opened more than two or three inches. The locking lever 25 is connected by a link 24 to a pivoted lever 22, which is connected by a closely-coiled spring 20 to the piston of cylinder 19. The piston is normally kept at the inner end of the cylinder 19 by a spring in the cylinder, but when the valve 11 is energized and pressure fluid is supplied to the cylinder the piston is forced out and the locking lever 25 is thus moved clear of the door arm 35, the spring 20 acting as a rod in compression. The locking lever 25 is held in its withdrawn position by a spring-controlled detent 30 engaging a cam lug 28 on the lever 25. When the valve 11 is de-energized, the piston of cylinder 19 is moved in by its spring, but locking lever 25 is held by the detent 30, so that spring 20 is extended. When the door nearly reaches its closed position after being opened, a lug on the door arm 35 engages an adjustable screw 33 on the detent 30 and withdraws the detent to allow the lever 25 to move to the locking position under the action of spring 20. The lever 22 also engages a sliding bar 48, to one end of which is connected a lever 59, Fig. 7, pivoted at 60, which operates a switch 64 to close a signalling circuit when the door is closed and locked. Mounted on the opposite end of the shaft 38 to the guides 41 is a hand-lever 53, the hub 52 of which is formed with a lug to engage a pin 51 fixed in the shaft 38. The shaft 38 can thus be rotated and the doors opened bv hand if the power fails, the locking lever 25 being operated through lever 59 and slide 48 by a cam surface 55 on the hand-lever hub 52 engaging a screw 62 carried by an extension of the switch-operating lever 59. The hand-lever need only be moved sufficiently to withdraw the locking lever 25 and to move the lever 42 from its horizontal position, the remainder of the movement being effected by direct manual operation of the door. A modified engine for the operation of two adjacent doors is shown in Figs. 14 and 18. The doors D are connected by fixed arms 112 and links 111 to arms 40 on the end of the shaft 38 ; in this case no resilient device is used with the levers, but the pivots of the links 111 could be made slidable against spring pressure on the arms 40. The locking lever is omitted, and the sliding bar 48 is extended to lock the doors by obstructing the passage of bolts 114 which are fixed to the doors and slide in guides 115. The sliding bar 48 is held clear of the bolts 114, when the doors are opened, by an arm 133, pivotally mounted and biassed by a spring 136 ; this arm is moved clear of the bar 48, when the doors are nearly closed, by engagement of a pin 135 on a lug on the door-operating shaft 38 with an arm 134<1> integral with arm 133, and the bar 48 is then moved into the locking position by the spring piston-rod of lock cylinder 19 as before. The hand-lever 53 in this case, in addition to its other functions, operates the plunger of the valve 18 by means of a link 118, working against a spring 120, connected to a rocking shaft 121 with an arm 122 which presses on a pin 95, Fig. 12, fixed to the solenoid core of the valve ; this enables the doors to be opened by power when the electrical control is not available.